From the badgers lining their “deep winter quarters” with dry leaves to the larch woods making “great splashes of golden flame”, Roald Dahl’s vision of November is laid out in his last book: a diary of the author’s year that has been republished for the first time in 20 years.

My Year, which Dahl wrote shortly before his death in 1990, has been out of print since 1998. Packed with illustrations by Quentin Blake, it deals with everything from the changing seasons to the pranks he pulled as a child on unsuspecting passers-by, moving through the months of the year as Dahl documents the flora and fauna around his house in Great Missenden in Buckinghamshire. The Roald Dahl Museum and Story Centre has collaborated with Penguin Random House and the Roald Dahl Story Company to bring the book back into print.

“A hot bath is the best place for all of us in the miserable month of January,” Dahl writes before moving through February – “the fiercest and bitterest month of all” – and March, when “halfway through the month most of the hedges are covered with a pale powdering of green as the little leaf buds begin to burst, and the pussy willows are smothered in yellow pollen”. Noting the mating habits of moles (“not a very attentive husband”), Dahl also details how he used to take eggs from nests as a boy, using a teaspoon to avoid leaving his smell behind; how he used to eat buttercups (“frighteningly hot, like mustard”); and how best to win at conkers: “I could go on for hours about the best shape to select for a fighting conker – always the flat sharp-edged one, never the big round fellow.”

Dahl, who laid out his childhood in the memoir Boy, gives readers further insight into his mischievous nature in My Year, describing how he would ride his motorbike in disguise on a Sunday at school, “sailing past the pompous prefects and the masters in their gowns and mortarboards”. He also describes how, with a Meccano set he received for Christmas, he once constructed a “bombing” device to terrorise pedestrians using the public footpath on his family’s land – hitting two women, each “with a revolting little Pekinese dog on a lead”.

Come December, the author of novels dealing with particularly unpleasant children, from Charlie and the Chocolate Factory to Matilda, is keen to express just how much he likes children who make their own Christmas cards. He isn’t, he adds, a fan of cards “that have on them a colour photograph of the senders standing proudly somewhere or other surrounded by their offspring … You can be half-blinded by the self-satisfaction shining out of their faces.”

Steve Gardam, director of the Roald Dahl Museum, said the book was “a little hard to categorise – part memoir, part guide to the countryside”.

“It’s the last book Roald wrote, and yet it’s the work of a writer still at the peak of his powers and clearly in love with his craft, the best way he knows to celebrate and reflect on his life and the natural world,” said Gardam, speculating that it might have fallen out of print as it became overshadowed by his children’s novels.

Having printed a limited run of 1,000 copies, Gardam said the museum had brought My Year back into print “to share the quality of the writing, and because it is so much a Buckinghamshire book”.

“What My Year also does is underpin Roald’s famous exhortation to ‘look at the world with glittering eyes’ and find magic in unlikely places. As a charity we want our visitors to understand Roald’s simple yet powerful creative process, and feel they can try it for themselves. It all starts with finding inspiration in the world around you, by seeing, noticing and wondering about the things right in front of you,” he said.